1. Field of the Invention
This invention relates to a method of identifying through an electronic identification system articles moving along a surface, particularly suitable for identifying metal pallets or containers moving over a loading floor, each article to be identified being provided with an electronic responder comprising a receiver circuit, a switching means connected thereto and control means for the switching means.
The present invention further relates to an electronic identification system for identifying articles provided with an electronic responder and moving along a surface, suitable in particular for application in articles containing much metal and/or a surface containing much metal, each electronic responder comprising a receiver circuit, a switching means connected thereto and control means for controlling the switching means, there being provided at least one transmitter/receiver device having an output circuit. The present invention is e.g. highly suitable for automatically identifying metal pallets and containers, as employed by the various airline companies, the moment they enter or leave an airplane.
This automatic identification has the object to detect early whether the pallets and containers entering the airplane are to be transported actually to a destination of the airplane in question and whether they pertain to the planned cargo. At the same time, an optimum stowage of the airplane cargo can be achieved and thereby a minimum fuel consumption, because the dimensions and weights of the thus identified pallets and containers to be loaded are known. These data, after identification, can be supplied, automatically or otherwise, to the onboard computer.
By using identification, for articles upon entry and upon leaving the airplane and by processing these data via an onboard computer, it is achieved that the airline company is independent of the facilities present at the airport concerned for effecting an optimum loading.
In connection with the relatively large amount of information to be read from the pallets and containers, as well as in connection with the rather rough operating conditions in all weather, and also on account of the unknown orientation of the pallet or the container, it is obvious to use an electronic responder, which transmits programmable or non-programmable information by means of electromagnetic waves to a transmitter/receiver apparatus.
2. Description of the Prior Art
Examples of such identification systems are described in Dutch patent applications 77,11891 and 86,01021 of Applicants, which describe systems consisting of a transmitter/receiver unit with transmitter/receiver and aerial system, as well as an electrical responder with aerial having no supply of its own in the form of a battery but being supplied through the electromagnetic interrogation field of the transmitter/receiver.
One problem is, however, that the known identification systems cannot be used without more ado for identifying articles which are entirely or partly electrically conductive, such as metal pallets and containers, moving over a metal floor, such as an airplane floor. The metal parts disturb a magnetic field, while moreover between the underside of the pallets or containers and the floor, there is mostly no or insufficient room to install aerials above the floor or underneath the underside of the pallets or containers.